Furnaces are one of the most popular heating systems on the market today due to their ability to use different fuel sources and their manageable upfront cost. Unfortunately, just like any other HVAC system, you’ll experience an issue with your furnace from time to time. If it’s blowing cold air, it could be due to these 11 issues.
1. System Starting Up
If you notice cold air is only coming from your vents when your furnace kicks on and then it turns to warm air, this may not be cause for concern. There is simply a delay between when your blower fan kicks on and starts moving cold air out of your ductwork and when heat starts to travel through the ducts. It should take less than a minute from the time your furnace kicks on until you start feeling warm air. If the warm air never comes, then you have an issue with your furnace.
2. Pilot Light Is Out
If you have an older gas furnace that still uses a pilot light for your furnace’s burner, the light may be out. In many cases, you can simply relight the pilot light by using the reset toggle assembly. When the pilot light cannot be lit, it typically indicates an issue with the fuel supply going to your furnace. An HVAC technician should assess this type of issue.
3. Dirty Flame Sensor
Newer gas furnaces use electric igniters that light the main burner for your system to start burning fuel. As a necessary safety component, there is a flame sensor. This sensor is meant to constantly monitor the burner to see if there is a flame. If it’s determined that there’s no flame, the gas supply going to your furnace will shut off. This is beneficial to prevent excess gas from accumulating inside your home.
The flame sensor can become dirty and no longer sense an active flame on the burner. It will shut off the gas supply even though there’s a flame, which will result in cold air blowing out of your furnace. In many cases, the flame sensor eye can be cleaned and go back to working like normal. If the flame sensor is faulty, it will need to undergo replacement.
4. Gas Line Issue
When there isn’t a consistent supply of gas going to your furnace, the burner is not going to stay lit. However, the furnace can still run and blow cold air. You could experience a couple of different issues with your gas line. It could have a clog at the orifice where gas is meant to come out to your furnace’s burner, which will prevent it from being fed to the burner for heat. There could be a leak in your gas line that isn’t allowing the gas to travel the whole way to your furnace. You may simply be low on gas.
5. Clogged Condensate Lines
Newer, high-efficiency furnaces come with built-in drain lines. These drain lines are specifically engineered to help with the removal of moisture from your home. Unfortunately, when any of the condensate lines have a blockage in them, it could cause your furnace’s burner to stop working and leave your furnace blowing out cold air into your home. The clog must be removed from the condensate line for your furnace to work effectively.
6. Ductwork Damage
Cold air doesn’t always indicate a problem with your furnace. In some cases, the problem may simply lie in your ducting. If your ductwork has developed one or more large leaks, it can allow hot air from your furnace to escape into your wall and floor cavities. This will result in cold air being delivered to your living spaces. It’s best to have a professional come in and seal up your ductwork to prevent that heat loss.
7. On vs. Auto Setting
You may simply have your thermostat on the wrong setting. Make sure that you have it on heating mode instead of cooling mode. Additionally, it should be put in auto mode instead of on mode. If you have your furnace in on mode, its blower components are going to run around the clock. Unfortunately, your furnace cannot run constantly, as it will overheat and shut off as a safety measure. When this happens, your system will blow cold air until your furnace cools down and goes back to heating again.
8. Internal Circuit Board Issue
Most modern furnaces have internal circuit control boards that are responsible for telling the furnace’s components what to do and when. Typically, when your thermostat determines that it’s time for your heating system to kick on, it will send a signal to the furnace’s blower and burner. If the circuit control board is malfunctioning, that signal could pass through to turn on the furnace’s blower but may not make its way to the furnace’s burner. This will result in the blower fan pushing cold air out of your vents without your furnace’s burner turning on.
9. Faulty Main Limit Switch
An important part of your furnace’s safety features is its main limit switch. This switch is responsible for turning off your furnace’s burner whenever it senses that your system is overheated. This allows air to continually blow through your vents but not be heated. Unfortunately, if your main limit switch starts to malfunction, you could turn off your furnace’s burner even though your furnace isn’t overheating.
10. Dirty Air Filter
Your furnace’s filter is specifically designed to remove harmful airborne contaminants from the air before it enters your furnace. This helps to ensure a safe operation process and protects the overall longevity of your furnace’s internal components. Unfortunately, when your furnace’s filter gets too packed full of debris and you don’t change it, it can put a massive strain on your heating system.
Your blower’s components are going to struggle to pull air through the extremely dirty filter. This could cause overheating of your furnace, which could trigger the main limit switch to shut off your furnace’s burner components. Fortunately, this is a very easy fix, as you simply need to install a clean furnace filter.
11. Closed Air Vents
It’s a common myth that closing off air vents in unused rooms of your home is an ideal way to reduce your heating bills during the wintertime. This simply isn’t the case, as closing air vents can cause your furnace to reduce its run-cycle time. This means that it may only run for a very short amount of time and then kick back off. If the furnace’s cycle is too short, it may only run long enough to push cold air out of your vents and never move hot air produced by the furnace completely out into your rooms. Fortunately, this issue is easily fixed by simply reopening any closed vents.
Reliable Furnace Service
Bumble Breeze offers reliable furnace services to homeowners in Las Vegas, NV. We can help with all your heating, cooling, plumbing, commercial, and indoor air quality needs. Contact our helpful staff today to book your next service consultation.
